(1) Field of the Invention
The present invention relates to an apparatus and method for tunnel current measurement taken simultaneously with electrochemical measurement. More particularly, it relates to an apparatus and method for detecting the tunnel current flowing between a sample to be investigated and a tip while measuring the electrochemical reaction by regulating the electric potential of the sample in a solution. Furthermore, it relates to scanning tunneling microscopy for producing a surface image of the sample from the detected tunnel current during the electrochemical reaction.
(2) Description of the Related Art
A technique of detecting the current of a sample by regulating the electrode potential of the sample and observing an electrochemical reaction is generally adopted, and apparatuses for using the technique are commercially available, for example, as a potentiostat and a polarography. A method of detecting a tunnel current by applying a voltage between a sample and a tip is also generally used, and a means for producing the surface image of the sample from the detected tunnel current is known as a scanning tunneling microscope. Such a scanning tunneling microscope has already been known from, e.g., U.S. Pat. No. 4,343,993 and measurement under a super high vacuum is carried out by using one. Recently, measurement in air and in a solution has also been carried out.
However, a method of detecting a tunnel current simultaneously with the measurement of an electrochemical reaction, such as electrochemical deposition, corrosion of an electrode, various reactions of an electrode, etc. had not been established heretofore and had been considered impossible.